The Sea to Summit Ether Light XT Air Sleeping Mat covered here is the non-insulated, discontinued version of the Ether Light XT line — an air-only pad with no reflective or synthetic fill, relying purely on the air trapped inside its Air Sprung Cells for cushioning. With an R-value of 1.2 (measured against Sea to Summit's own legacy standard rather than the current ASTM protocol), it offers minimal thermal resistance and is really a warm-weather piece, not a shoulder-season pad.
In regular size it measures 183×55 cm, tapered mummy-shaped to save material, with 10 cm of loft and a packed size of just 19×9 cm at 390 g — a genuinely ultralight number for an air pad of this length. The multi-function valve handles both inflation and deflation, a stuff sack and repair kit are included, though a pump sack is not. Because it's air-only, insulation depends entirely on air temperature, so it suits summer backpacking, warm-climate thru-hikes, or use as a supplementary layer under a warmer pad rather than a stand-alone choice for cold nights.